1. Field of the Invention
The invention relates to a driving device, and more particularly to a driving device for controlling the rotation of a single phase motor.
2. Description of the Related Art
Heat generated in a computer raises proportionally to increase in power requirements of the components inside of the computer. Among them, the central processing unit (CPU) generates the most heat. When the number of the transistors in a CPU increased from about one hundred thousand in the 386 generation CPU to about fifty million in the Pentium 4 generation CPU, the surface temperature of the CPU reached 50-80° C., and the temperature inside of the CPU reached 80° C. on average, and sometimes even 100° C. Thus, requirements for heat dissipation of a CPU have increased, and several types of heat dissipation systems for computers have been developed. Among the developments, the motor controlled fan is the most popular one used for heat dissipation.
Conventionally, the speed of a fan is controlled according to the driving current provided by the motor control device. Different levels of driving current, drives different fan speeds. Accordingly, different heat dissipation results can be achieved. Thus, accurately generating driving current to appropriately drive motor speed and efficiently providing the best heat dissipation results according to the temperature of electrical components, have become the most important topic in the heat dissipation field.